Strain-Induced Ultrahard and Ultrastable Nanolaminated Structure in Nickel
Strain-Induced Ultrahard and Ultrastable Nanolaminated Structure in Nickel
复制标题
镍中应变诱导的超硬和超稳定纳米层压结构
DOI：
10.1126/science.1242578
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发表时间：
2013-10-18
期刊：
影响因子：
56.9
通讯作者：
Lu, K.
中科院分区：
文献类型：
--
作者：
Liu, X. C.;Zhang, H. W.;Lu, K.
重塑性变形可以细化金属晶粒并使其变得非常坚固。但应变引起的细化在大应变下饱和，形成具有随机方向的三维超细晶粒 (3D UFG) 结构。由于晶界迁移率的增强，这种微观结构的进一步细化受到限制。在块状镍的顶部表面层应用具有高应变梯度的极高速率剪切变形，从而诱导出二维纳米级层状结构。片层之间具有小角度边界的强纹理纳米层压结构（平均片层厚度为 20 纳米）是超硬和超稳定的：它的硬度为 6.4 吉帕斯卡（高于任何报道的 UFG 镍的硬度），粗化温度比 UFG 镍高 40 开尔文。
Heavy plastic deformation may refine grains of metals and make them very strong. But the strain-induced refinement saturates at large strains, forming three-dimensional ultrafine-grained (3D UFG) structures with random orientations. Further refinement of this microstructure is limited because of the enhanced mobility of grain boundaries. Very-high-rate shear deformation with high strain gradients was applied in the top surface layer of bulk nickel, where a 2D nanometer-scale laminated structure was induced. The strongly textured nanolaminated structure (average lamellar thickness of 20 nanometers) with low-angle boundaries among the lamellae is ultrahard and ultrastable: It exhibits a hardness of 6.4 gigapascal-which is higher than any reported hardness of the UFG nickel-and a coarsening temperature of 40 kelvin above that in UFG nickel.